I wanna say Bill Nye had a little contraption that explained this phenomenon. A cup with a piston on one end that vibrated. The top part of the cup had a ring in the center where little balls in the cup could fit. The piston represented the temperature (energy). Even at a lower temperature, some balls could randomly fly into the little hole and into the other partition. Turning the temperature up (increasing the speed and power of the piston) made more balls more frequently "evaporate." I wish I could find that demonstration again.